This book deserves more than five stars.
The Rule of Three is well-documented, easy to read and understand, is filled with practical advice that can be used for many strategic purposes. Regardless of your industry, the size of your business, and your ambitions, you will be well rewarded by the time you spend with this book. It will provide a useful perspective of the sort that you probably have gained from books like The Innovator's Dilemma, The Discipline of Market Leaders, and The New Market Leaders.
For a quick overview of the book, I suggest you begin by reading the clear summary of key points on pages 200-202.
The idea that most industries will eventually be dominated by three broad-scale suppliers with a few profitable specialists was one I first heard from Bruce Henderson, CEO of The Boston Consulting Group, about 1972. My quick look around at the time showed that this pattern did frequently occur (domestic autos, breakfast cereal, and beer came to mind then). This industry structure is more often present now than it was then due to the massive consolidations through acquisitions and business failures that have happened in the United States and world wide. Since learning about the empirical observation, I have usually seen the point applied to the questions of how a market leader could most effectively put pressure on the third largest company in the industry and vice versa. The Rule of Three goes well beyond that scope.
As a result, I was delighted to see that the authors of this fine book have provided extensive empirical documentation of their observations by listing many different industries where this structure occurred, case examples from dozens of old and new industries, and definitions of what can trigger this development. Of particular value to readers will be the detailed descriptions of the strategies that are most likely to succeed and fail, and the most frequent causes of those outcomes.
The detailed observations were usually spot on. I only detected a few places where I disagreed with points that were made. For example, EMC was listed in an appendix as being in the computer peripheral industry along with companies that mostly make PC peripherals. I see EMC as mainly competing instead with the likes of IBM, Hewlett-Packard, Fujitsu, Dell and Storage Networks. The authors also argue that the large general competitors usually enjoy a stock-price multiple over the specialist, niche players who have high returns. I would argue that it is usually just the opposite.
I thought that the problem of the #4, #5, #6 and so forth general suppliers was well described as falling into "the ditch" where the lowest returns on assets are earned. These companies lack the benefits of being a specialist and the scale of being a leader. Often, they succumb. If they can merge to become or join a top company, then the situation may change.
I was pleased to see that the authors described how a company may "change the rules" citing how Starbucks has made progress against the traditional coffee suppliers (Maxwell House, Folger's, and Nestle) by providing more accessible, better quality coffee at a higher price. The main opportunity to strengthen the book would have been to discuss this point with more examples and in more detail.
I also enjoyed the discussion of how specialist companies can be lured into chasing unprofitable market share, and falling by the wayside as a result.
Many authors with an empirical theory like this one would try to avoid talking about situations where one company has almost all the market share (such as occurs in personal computer software), or two companies get almost all the business (as in commercial airframe manufacturers), or even four (as often occurs in Europe and Japan). The authors actually strengthened their main point by examining those exceptions to their rule, and showing the influences that made these results occur.
As someone who is interested in uncontrollable forces that can influence industry structure, I thought that the focus here was good although much simpler than the detailed lists that Professor Michael Porter provides.
Having understood these points, I encourage you to think through how you could use these forces against the current market leaders. As the book suggests, the leaders' efficiencies and size make them vulnerable to nimble competitors offering new business models that serve customers and stakeholders in more ways than by lowering costs. Like the cataclysmic event that killed off the dinosaurs, new business models can doom the existing leaders to being poorly fit for the new environment.
Look for the ultimate competitive advantage!